Hello everybody,how can I solve the following problem using the "pressure drop and flow calculator"?

I have a water tank with a water column of 50 meter.At the bottom of the water tank is a straight vertical pipe of 800 meter length with a diameter of 0.3 meter.Now I want to calculate the flow rate.

The question is what to use as pressure (p1-p2). Do I have a total water column of 850 mWS (50 mWS in the tank + 800 mWS in the vertical pipe) or is it just 50 mWS? Can I use the calculator?If for example the total water column would be 50 mWS. Would than p1 =50 mWS and p2=0 mWS

If the tank is open to atmosphere your p1=0.But as you do not have option to enter height in calculator, you can enter 50 + 800 mWS as p1. p2 = 0.Also you have K1 = 0.5 (pipe entrance) and K2 = 1 (pipe exit) with total of K1 + K2 = 1.5 total resistance coefficient.